Effects of environmental factors on functional properties of Chinese chestnut (Castanea mollissima) protein isolates

Chestnut is a nutritious food source. The effects of physical force on the functional properties of chestnut protein isolates were investigated. Maximum protein solubility, emulsion activity, emulsion stability, and foam capacity, as well as minimum protein solubility, emulsion activity, and foam capacity were observed at pH 12 and 4, respectively. The highest foam stability rate was observed at pH 4, particularly after 60 min. At the same ionic strength, the protein in NaCl showed better solubility than CaCl2. The presence of Ca2+ significantly enhanced the foam capacity and stability of chestnut protein, and the maximum foam capacity was 77.3 % at 0.8 mol/L ionic strength of Ca2+. Sugar could enhance foam stability but inhibit foam capacity, and appropriate concentrations (0.05–0.1 mol/L) increased emulsion activity and stability. The chestnut protein isolates had good emulsification and foam properties, and can be used as additives in food products requiring specific functional properties.